Copper-silicon-zinc-lead alloy



Patented ar. 39,. 1937 par 2p75fi5 QQIPIPER-SELHCQN-C-LEAD Y William llil. Bassett, deceased, late of Ch h Conn, by Sarah lnl. Bassett, Shes, executrix; said lBassett assignor to The Conn...

can Brass Company, Waterbury, Conn a corporation of Coecticut I No Drawing.

1933, Serial N (Original application November 25,

. 699,710. Divided and t application December 15, 1936, Seriai No.

3 (Claims.

This invention relates .to copper base alloys containing silicon and zinc, and has for its chief object to improve certain characteristics of such alloys, and particularly their machinability or 5 free cutting properties. The free cutting properties of these copper base alloys are secured with little or no depreciation of their physical properties by the addition of lead in relatively small amounts.

This application is a division of the prior application of William H. Bassett for Copper silicon alloys filed November 25, 1933, Serial No. 699,710.

A number of copper base alloys containing silicon have gone into quite extensive use, it being found that the addition of silicon up to certain amounts to copper produced alloys which were highly resistant to the chemical action of certain acids and other corrosive liquids. It was, however, found that the addition of silicon rendered the alloy hard and very brittle and dimcult or practically impossible to work, and other elements such as zinc were added to overcome these dimculties and improve other properties of the alloy such as strength, toughness and so forth, and still retain the resistance to corrosion. It was found that for practical purposes the range of silicon was up to approximately 6.5%, and his invention therefore relates to copper base alloys containing from approximately 0.1% to approximately 6.5% silicon, and 1% to 12% zinc.

It has been known to improve the machining qualities of copper or brass by the addition of lead, but it has been generally considered and also the literature would indicate that in alloys containing silicon lead would be thrown out of the mixture by the silicon. This was also indicated where there has been a. mixture of leaded scrap with copper silicon alloys. In other words it was generally supposed that with silicon present the lead would settle to the bottom of the crucible or furnace due to its high density. He has found, however, that with small amounts of lead in copper base alloys containing silicon and who in the amounts above noted the lead is dispersed as fine particles throughout the mass. greatly improving its machinability or free cutting properties. He has found that this effect is secured with amounts of lead from approximately 0.1% to approximately 1.5%, the pre- 5 ferred range being from approximately 0.25% to approximately 0.4%, as above about 0.4 or 0.45% lead it is dimcult or practically impossible to work the alloy in mill practice.

Zinc was added to the copper silicon alloy to produce alloys which could be worked either hot or cold and therefore were less brittle while still remaining highly resistant to the corrosive action of certain acids and other corrosive liquids. It also rendered the alloys harder, tougher, stronger and more elastic than the common brasses. These alloys with the lower zinc contents are hard, malleable, ductile and tough. Increasing the zinc gives alloys which are stronger, harder, more elastic but less malleable. The addition of zinc also gives sounder castings as the metal has less tendency to absorb furnace gases than copper-silicon alloys containing no zinc and the resistance to the corrosive action of certain liquids is also improved. The hardness as cast increases with additions of zinc up to about 12%.

These alloys were found to be dimcult tomachine as among other things the chips were tough and came off in long continuous spirals tending to clog the tools, and the tools would not stand up and cutting speed was relatively low. It was found, however, that by the addition of the above named quantities of lead to these alloys they were rendered much more free cutting, and the chips instead of coming off in long continuous spirals broke up into short lengths easily clearing the tool, and in short converted the alloys into free cutting alloys with little or no depreciation of their physical properties, such as strength, toughness, workability, and resistance V to corrosion.

Having thus set forth the nature of his invention, what he claims is:

l. A copper base alloy which is characterized by free cutting properties and resistance to corrosion comprising approximately 0:1% to 6.5% silicon, 1% to 12% zinc, 0.1% to 0.45% lead, and balance copper.

2. A copper base. alloy which is workable and characterized by free cutting properties and resistance to corrosion comprising approximately 0.1% to 6.5% silicon, 1% to 12% zinc, 0.25% to 0.4% lead, and balance copper.

3. A wrought metal article composed of a copper base alloy characterized by free cutting properties and resistance to corrosion comprising approximately 0.1% to 6.5% silicon, 1% to 12% and balance copper.

SARAH H. BASSE'I'I, Ezecutria: o the Last Will and Testament of William H. Bassett, Deceased.-

zinc, 0.1% to 0.4% lead, 

